in a 1066FSB system, the actual BUS speed is 266MHz. intel CPUs quad-pump the data giving an effective FSB of 1066. the RAM is still DDR (double data rate) which means that it runs an effective speed of twice the system BUS at DDR533

in an 800FSB system the actual BUS speed is 200MHz, and the RAM runs at DDR400

if DDR memory was capable of running at 1066, the actual system BUS would have to be 533, giving an effective CPU FSB of 2132 and a RAM speed of DDR1066. or if such a thing existed, the RAM would have to be QDR (quad data rate) memory to run at 1066MHz with a 266MHz system BUS

i hope this helps explain it. its not the mobo manufacturers fault, it simply the way DDR works.